1. Technical Field
The present invention relates to an authentication apparatus and the like capable of authenticating a user registered in advance.
2. Related Art
It is important to ensure rigid security. For example, in a system enabling access to highly confidential personal information, it is essential to provide an apparatus that authenticates users registered in advance and rejects those accessing illegally.
On the other hand, high degree of accuracy in authentication and burden borne by user for the authentication are likely to be trade-off. For example, when a user is repeatedly requested to input a password in order to ensure authentication of the user, the burden borne by the user increases.
In order to solve the above trade-off, so-called “biometrics authentication” attracts attention. That is, an authentication apparatus performing authentication using biometrics information unique to each user such as fingerprint, vein and pupil is widely studied as an apparatus capable of achieving not only rigid security but also simple authentication (user's convenience). Among the above authentication apparatuses, “face authentication” using user's face is extensively studied as an authentication method causing the least burden borne by the user.
For example, Japanese Unexamined Patent Publication No. 2010-92119 (published on Apr. 22, 2010) describes a control apparatus quickly performing collation processing of input data and registered data while maintaining a high degree of security and collation accuracy. Japanese Unexamined Patent Publication No. 2011-233119 (published on Nov. 17, 2011) describes a measuring apparatus that achieves robust and high-speed attribute identification in a face direction of a subject.
Further, Japanese Unexamined Patent Publication No. 2003-141542 (published on May 16, 2003) describes a collation apparatus capable of maintaining a certain level of collation performance even when a similar face pattern exists in a dictionary for face collation.
However, the face authentication system using user's face as biometrics information involves the following two problems.
The first problem is that, in a classifier used in an authentication apparatus, the generalization performance and the identification performance are trade-off. More specifically, for example, when the classifier is designed to achieve identification performance even when a user executes face authentication in a manner different from a face image registered in advance (a case where the user registers a face image without wearing glasses, and the user tries to perform authentication with glasses on), the classifier is unable to identify the user under a particular condition, and the authentication accuracy of the authentication apparatus is extremely degraded.
The second problem is that a condition for selecting the classifier is not always given before the classifier performs identification. For the first problem, the following solution may be considered: the authentication apparatus has multiple classifiers specialized in particular conditions, and selects and uses the multiple classifiers in accordance with the condition. However, the condition for the selection may not be given before the selection.
None of Japanese Unexamined Patent Publication No. 2010-92119, Japanese Unexamined Patent Publication No. 2011-233119, and Japanese Unexamined Patent Publication No. 2003-141542 solves the first problem and the second problem explained above at the same time. For example, the control apparatus described in Japanese Unexamined Patent Publication No. 2010-92119 narrows down registration data by high-speed but low accuracy collation processing, and then switches to low-speed but high accuracy collation processing, thus trying to solve the first problem. However, the second problem is not considered. The technique described in Japanese Unexamined Patent Publication No. 2011-233119 or Japanese Unexamined Patent Publication No. 2003-141542 solves either one of the problems.
The present invention is made in view of the above problems, and it is an object of the present invention to provide an authentication apparatus and the like achieving highly-accurate face authentication in wide range of circumstances by solving the first problem and the second problem at the same time.